Abstract: An air flow control apparatus is disclosed which is characterized by essentially zero leakage in its closed position, and by minimal air resistance in its open position. The apparatus includes a housing having an interior framework which defines a plurality of troughs of V-shaped cross section, and with each side of each trough including an opening. A closure is associated with each trough, which includes a pair of pivotally mounted plates which are movable between a spread apart position covering and closing the openings in the trough, and a collapsed position wherein the plates are substantially aligned with each other and spaced from the associated openings to permit free air flow therethrough.

Abstract: A housing for HEPA filters is disclosed, which includes a side access opening for receiving one or more filters, and a filter clamping assembly for seating and unseating each of the filters against its seal. The clamping assembly comprises a pair of filter clamping mechanisms extending transversely across the interior of the housing and along the top and bottom side walls, respectively. Also, a handle is pivotally mounted between the two clamping mechanisms adjacent the opening, and the handle is connected to each clamping mechanism such that rotation of the handle serves to actuate the mechanisms. In one embodiment, the handle is releasably connected to the two mechanisms, and the mechanisms are releasably mounted to the top and bottom side walls, whereby the entire assembly may be disassembled and removed from the housing through the side access opening to permit the repair or replacement of a defective component.